ABSTRACTNestmate recognition is the basis for cooperation within social insect colonies. Quantitative variation in cuticular hydrocarbons (CHCs) is used for nestmate recognition in ants and other social insects. To infer genetic effects on CHC variation, we tested for association between CHCs and polymorphic genetic loci to identify potential quantitative trait loci (QTL). We carried out a genome wide association study (GWAS) of CHCs in the desert ant Cataglyphis niger by sampling 47 colonies, fully sequencing six workers from each colony, and measuring the relative amounts of their CHCs. Under the Gestalt colony odor model, social interactions between nestmates, in which CHCs are transferred and mixed, are essential in creating a uniform colony CHC profile. Therefore, we carried out a second GWAS between the colonies and their Gestalt odor by averaging nestmate genotypes and comparing them to their averaged CHC amounts. Together, the two analyses identified 99 candidate QTLs associated with 18 out of 34 CHCs. Thirteen clusters of two to four QTLs located within 10 cM of each other were identified, seven of which contained QTLs from both analyses. We conclude that nestmate recognition cues are complex quantitative colony‐level traits with a significant genetic component to their phenotypic variation and a highly polygenic architecture.

Navigation is crucial for animal survival, and despite their small brains, insects are impressive at it. For example, desert ants acquire environmental information by learning to walk before foraging, enabling them to return home accurately over long distances. These learning walks involve multimodal sensory experiences and induce neuroplastic changes in the Central Complex (CX) and the Mushroom Body (MB) of ants’ brains, making them a key topic in behavioural science, neuroscience, and computational modelling. To address unresolved questions in how ants integrate sensory cues and adapt navigation strategies, we propose a computational model that achieves multisensory integration during learning walks. Central to this model is a novel Learning Vector mechanism that dynamically combines visual, olfactory, and path integration inputs to guide movement decisions. Specifically, the agent in our model determines the degree to which it deviates from the homing direction by evaluating the familiarity of the environment. In this way, agents could strike a balance between their tendency to explore and the need to return safely to the nest. Our model replicates key features reported in biological studies and accounts for individual and inter-species variability by tuning parameters such as cue preferences and environmental parameters. This flexibility enables the simulation of species-specific learning walks and supports a unified view of sensory integration and behavioural adaptation. Moreover, it yields testable predictions that may inform future investigations into the neural and behavioural mechanisms underlying insects’ learning walks. How the proposed model could be adapted for robotics navigation has also been discussed.

Background:Ants are among the most widely distributed eusocial insects, and desert ants, in particular, serve as important model organisms for studying animal navigation. Methods: In this study, we provide high-quality de novo transcriptomes for eight ant species: Cataglyphis aenescens (Nylander, 1849), Formica approximans Wheeler, 1933, Lasius coloratus Santschi, 1937, Proformica mongolica (Emery, 1901), Proformica muusensis Zhu, Wu, Duan & Xu, 2022, Tapinoma geei Wheeler, 1927, Tapinoma rectinotum Wheeler, 1927, and Tetramorium tsushimae Emery, 1925. Results: The GC content of coding sequences (CDSs) ranged from 43.61% to 46.20%, indicating a slightly AT-rich composition. Codon usage analysis identified 27 to 33 optimal codons per species, the majority of which ended with A or U. Conclusions: These transcriptomic resources provide critical insights into codon usage bias and establish a foundation for future research on molecular evolution, gene regulation, and environmental adaptation in ants inhabiting fragile desert ecosystems.

Movement in life is usually carried out by effectors, body parts that carry out action such as flagella, archaella, cilia, whole bodies that sinuate, or limbs, moving regularly and periodically in an oscillator system. For navigation and orientation, the oscillations that generate movement are sometimes interrupted by stops, turns, or both. I review evidence in bacteria, archaea, and one animal, the Australian desert ant Melophorus bagoti, that such interruptions to forward movement take place as random-rate or Poisson processes. At every moment in time, there is a constant probability of the event taking place. On looking for explanations for such random-rate events, some evidence suggests that the bacterium Escherichia coli relies on stochastic or random fluctuations to generate turns. I conjecture that relying on noise makes a cheap mechanism in the sense that no dedicated mechanism for generating occasional interruptions is required. Random processes mostly come ‘for free’. The data are too sparse and uncertain for archaea and ants to attempt any explanation. It is not necessary to rely on noise or stochastic processes to produce what look like random fluctuations; various nonlinear mechanisms might do that. My call to action to those studying behaviour is to examine much more the interval or duration of time between events.

How ants, wasps and bees rapidly form visual routes represents an enduring mystery as well as a powerful example of the abilities of small brains. Here, we detailed a previously uncharacterized behaviour, ‘lookbacks’, which is theorized to underly rapid bidirectional route learning in desert ants. During these lookbacks, foragers stop forward movement to their goal location, turn and fixate their gaze on their origin, often for only 150–200 ms. This turn appears to be a period for learning the inbound route. Route formation relies on acquiring visual cues and comparing panoramic view memories with the current view. Although the nest panorama is learned during preforaging learning walks, during which naïve ants often fixate their gaze towards the nest, route following requires separate behaviours to learn route-based views. We untangle how route formation occurs in naïve desert ant, Melophorus bagoti, foragers during the first foraging trips by focusing on these lookback behaviours and their potential function in facilitating visual learning. Lookbacks were highly associated with the first few foraging trips and were concentrated in areas where the visual scene changed rapidly, resulting in increased unfamiliarity among naïve foragers. Analysis of gaze directions during lookbacks shows foragers pause intermittently, fixating their gaze in multiple directions during the turn with the longest of these being back at their origin, likely learning these views during their first foraging trips. We discussed the structure of lookbacks and how they may prime visual learning in ants and other insects. • Lookback behaviours associated with route formation and view learning. • Lookbacks occur in naïve ants in areas of rapid visual change. • Lookbacks involve foragers fixating their gaze back in the nest direction. • Lookbacks combine rotation and fixations, potentially priming view learning.

Solitary foraging insects such as desert ants rely heavily on vision for navigation. Although ants can learn visual scenes, it is unclear what cues they use to decide whether a scene is worth exploring at the first place. To investigate this, we recorded the motor behaviour of Cataglyphis velox ants navigating in a virtual reality setup and measured their lateral oscillations in response to various unfamiliar visual scenes under both closed-loop and open-loop conditions. In naturalistic-looking panorama, ants display regular oscillations as observed outdoors, allowing them to efficiently scan the scenery. Manipulations of the virtual environment revealed distinct functions served by dynamic and static cues. Dynamic cues, mainly rotational optic flow, regulated the amplitude of oscillations but not their regularity. Conversely, static cues had little impact on the amplitude but were essential for producing regular oscillations. Regularity of oscillations decreased in scenes with only horizontal, only vertical or no edges, but was restored in scenes with both edge types together. The actual number of edges, the visual pattern heterogeneity across azimuths, the light intensity or the relative elevation of brighter regions did not affect oscillations. We conclude that ants use a simple but functional heuristic to determine whether the visual world is worth exploring, relying on the presence of at least two different edge orientations in the scene.

Polarization photodetectors (pol-PDs) have widespread applications in geological remote sensing, machine vision, biological medicine, and so on. However, commercial pol-PDs use bulky and complicated optical systems with lenses, polarizers, and mechanical spools, which are complex and cumbersome, and respond slowly. Inspired by the desert ants' compound eyes, we developed a single-shot pol-PD based on four-directional grating arrays capped perovskite single-crystal thin film without other standard polarization optics. Our pol-PD has a high detectivity, two orders of magnitude greater than that of commercial photodetectors, and exhibits high polarization sensitivity. The high performance of our pol-PD is due to the highly crystalline perovskite single-crystal thin film and regular nanograting structure, made by a nanoimprinting crystallization method. Our single-shot pol-PD is a compact on-chip optoelectronic device that demonstrates excellent performance in a wide range of applications including accurate bionic navigation, sharp image restoration in hazy scenes, stress visualization of polymers, and detection of cancerous areas in tissues without histological staining.

Spatial orientation based on the geomagnetic field (GMF) is a widespread phenomenon in the animal kingdom, predominantly observed in long-distance migrating birds,1 sea turtles,2 lobsters,3 and Lepidoptera.4,5 Although magnetoreception has been studied intensively, the mechanism remains elusive. A crucial question for a mechanistic understanding of magnetoreception is whether animals rely on inclination or polarity-based magnetic information. Inclination-based magnetic orientation utilizes the angle between the magnetic field lines and gravity, indicating poleward and equatorward. In contrast, polarity-based magnetic orientation allows animals to detect the polarity of the GMF, the north and south direction of the field vector. Cataglyphis desert ants are excellent experimental models for testing whether magnetic inclination or polarity of the magnetic field is used for navigation. Desert ants are solitary foragers with exceptional navigational skills.6 When the ants leave their underground nest for the first time to become foragers, they perform learning walks for up to threedays to learn the visual panorama and calibrate their compass systems.7,8 The ants repeatedly stop their forward movement during learning walks for performing turns (pirouettes), interrupted by stopping phases. Gaze directions during the longest stopping phases are directed toward the nest entrance.9 We experimentally manipulated look-back behavior systematically by altering polarity or inclination of the GMF. We demonstrate that Cataglyphis ants, contrary to most other insects studied,10 possess a polarity-sensitive magnetic compass, making them ideal experimental models for narrowing down the evidence for particle-based mechanisms underlying magnetosensation in this insect.

Desert ants are known to rely heavily on vision while venturing for food and returning to the nest. During these foraging trips, ants memorize and recognize their visual surroundings, which enables them to recapitulate individually learned routes in a fast and effective manner. The compound eyes are crucial for such visual navigation; however, it remains unclear how information from both eyes are integrated and how ants cope with visual impairment. Here, we manipulated the ants' visual system by covering one of the two compound eyes and analyzed their ability to recognize familiar views. Monocular ants showed an immediate disruption of their ability to recapitulate their familiar route. However, they were able to compensate for this nonnatural impairment in a few hours by engaging in an extensive route-relearning ontogeny, composed of more learning walks than what naïve ants typically do. This relearning process with one eye forms novel memories, without erasing the previous memories acquired with two eyes. Additionally, ants having learned a route with one eye only are unable to recognize it with two eyes, even though more information is available. Together, this shows that visual memories are encoded and recalled in an egocentric and fundamentally binocular way, where the visual input as a whole must be matched to enable recognition. We show how this kind of visual processing fits with their neural circuitry.

Many ant species can respond to dramatic changes in local conditions by relocating the entire colony to a new location. While we know that careful learning walks enable the homing behavior of foraging ants to their original nest, we do not know whether additional learning is required to navigate to the new nest location. To answer this question, we investigated the nest relocation behavior of a colony of Australian desert ants (Melophorus bagoti) that relocated their nest in response to heavy rainfall in the semidesert terrain of Alice Springs. We identified five types of behavior: exploration between nests (Old-to-New nest and New-to-Old nest), transport from Old to New nest, and relearning walks at Old and New nests. Initially, the workers performed relearning walks at the Old nest and exploratory walks between the Old and New nests. Once they completed the exploratory walks, the workers transported resources and brood to the new nest. Finally, we observed the workers performing relearning walks at the New nest. While the relearning walks at the Old nest were slow and appear to enable exploratory walks to the New nest, the relearning walks at the new nest were faster and appeared to enable homing from foraging trips. These observations shed insight on how learning helps these ants to respond to sudden changes in their environment.

The Central Australian red honey-pot ant Melophorus bagoti maintains non-cryptic ground-nesting colonies in the semi-desert habitat, performing all the activities outside the nest during the hottest periods of summer days. These ants rely on path integration and view-based cues for navigation. They manage waste by taking out unwanted food, dead nestmates, and some other wastes, typically depositing such items at distances > 5 m from the nest entrance, a process called dumping. We found that over multiple runs, dumpers headed in the same general direction, showing sector fidelity. Experienced ants dumped waste more efficiently than naive ants. Naive individuals, lacking prior exposure to the outdoor environment around the nest, exhibited much scanning and meandering during waste disposal. In contrast, experienced ants dumped waste with straighter paths and a notable absence of scanning behaviour. Furthermore, experienced dumpers deposited waste at a greater distance from the nest compared to their naive counterparts. We also investigated the navigational knowledge of naive and experienced dumpers by displacing them 2 m away from the nest. Naive dumpers were not oriented towards the nest in their initial trajectory at any of the 2 m test locations, whereas experienced dumpers were oriented towards the nest at all test locations. Naive dumpers were nest-oriented as a group, however, at the test location nearest to where they dumped their waste. These differences suggest that in red honey ants, learning supports waste disposal, with dumping being refined through experience. Dumpers gain greater spatial knowledge through repeated runs outside the nest, contributing to successful homing behaviour.

Spatial and temporal distribution patterns of ants (Hymenoptera: Formicidae) in Gobi Desert ecosystems, Northwest China

We reliably judge locations of static objects when we walk despite the retinal images of these objects moving with every step we take. Here, we showed our brains solve this optical illusion by adopting an allocentric spatial reference frame. We measured perceived target location after the observer walked a short distance from the home base. Supporting the allocentric coding scheme, we found the intrinsic bias , which acts as a spatial reference frame for perceiving location of a dimly lit target in the dark, remained grounded at the home base rather than traveled along with the observer. The path-integration mechanism responsible for this can utilize both active and passive (vestibular) translational motion signals, but only along the horizontal direction. This asymmetric path-integration finding in human visual space perception is reminiscent of the asymmetric spatial memory finding in desert ants, pointing to nature’s wondrous and logically simple design for terrestrial creatures.

Precise and reliable autonomous navigation in a GPS-denied environment is critical to unmanned systems. The idea of combining SINS, the polarized navigation system (PNS), and the odometer (OD) inspired by desert ants has been proven to be effective for autonomous navigation. However, there are two major challenges for polarization navigation nowadays: inaccurate modeling and obtaining reliable heading information when some sensor channels are blocked. Aiming at these two problems, a tightly-coupled solution for SINS/PNS is proposed in this paper. To obtain a refined integrated navigation system model, the installation errors between the inertial units and PNS, and polarization angle calculation errors are analyzed and modeled for SINS/PNS. Then, to quickly gain the accurate state estimation, an improved iterative unscented filtering method is devised. In particular, the sigma-point updating step with the conditional distribution of high-dimensional Gaussian distribution random variables is developed, which employs partial states to sample in each iteration to reduce the calculation burden. Finally, a detection and elimination mechanism for the abnormal light channels is provided to enhance the reliability of the integration in the presence of a light blockage. The optical channels for navigation are chosen using this mechanism depending on the difference between the predicted and measured incident light intensities. The results in both simulations and outdoor experiments show that the proposed method provides a higher heading estimation accuracy than the traditional SINS/PNS navigation method. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This article is motivated by the inaccurate modeling and obtaining reliable heading in the presence of light occlusion for the polarization navigation. Various integrated navigation algorithms based on polarized skylight have been widely developed. However, the complex environment and inaccurate modeling limit the application of the polarization navigation. This article gives a novel accurate modeling method and reliable navigation algorithm. Tightly-coupled model with installation errors and the polarization angle error aims to improve the accuracy of the polarization navigation model. The improved iterative unscented Kalman filter is utilized to quickly obtain accurate state estimation. And the light detection and elimination mechanism is used to select normal light channels to navigate in the presence of light blockage. This navigation method can also extend the application of the polarization navigation.

Desert ants stand out as some of the most intriguing insect navigators, having captured the attention of scientists for decades. This includes the structure of walking trajectories during goal approach and search behaviour for the nest and familiar feeding sites. In the present study, we analysed such trajectories with regard to changes in walking direction. The directional change of the ants was quantified, i.e. an angle θ between trajectory increments of a given arclength λ was computed. This was done for different length scales λ, according to our goal of analysing desert ant path characteristics with respect to length scale. First, varying λ through more than two orders of magnitude demonstrated Brownian motion characteristics typical of the random walk component of search behaviour. Unexpectedly, this random walk component was also present in - supposedly rather linear - approach trajectories. Second, there were small but notable deviations from a uniform angle distribution that is characteristic of random walks. This was true for specific search situations, mostly close to the (virtual) goal position. And third, experience with a feeder position resulted in straighter approaches and more focused searches, which was also true for nest searches, albeit to a lesser extent. Taken together, these results both verify and extend previous studies on desert ant path characteristics. Of particular interest are the ubiquitous Brownian motion signatures and specific deviations thereof close to the goal position, indicative of unexpectedly structured search behaviour.

Many animal species rely on the Earth's magnetic field during navigation, but where in the brain magnetic information is processed is still unknown. To unravel this, we manipulated the natural magnetic field at the nest entrance of Cataglyphis desert ants and investigated how this affects relevant brain regions during early compass calibration. We found that manipulating the Earth's magnetic field has profound effects on neuronal plasticity in two sensory integration centers. Magnetic field manipulations interfere with a typical look-back behavior during learning walks of naive ants. Most importantly, structural analyses in the ants' neuronal compass (central complex) and memory centers (mushroom bodies) demonstrate that magnetic information affects neuronal plasticity during early visual learning. This suggests that magnetic information does not only serve as a compass cue for navigation but also as a global reference system crucial for spatial memory formation. We propose a neural circuit for integration of magnetic information into visual guidance networks in the ant brain. Taken together, our results provide an insight into the neural substrate for magnetic navigation in insects.

The Australian red honey ant, Melophorus bagoti, stands out as the most thermophilic ant in Australia, engaging in all outdoor activities during the hottest periods of the day during summer months. This species of desert ants often navigates by means of path integration and learning landmark cues around the nest. In our study, we observed the outdoor activities of M. bagoti workers engaged in nest excavation, the maintenance of the nest structure, primarily by taking excess sand out of the nest. Before undertaking nest excavation, the ants conducted a single exploratory walk. Following their initial learning expedition, these ants then engaged in nest excavation activities. Consistent with previous findings on pre-foraging learning walks, after just one learning walk, the desert ants in our study demonstrated the ability to return home from locations 2 m away from the nest, although not from locations 4 m away. These findings indicate that even for activities like dumping excavated sand within a range of 5–10 cm outside the nest, these ants learn and utilize the visual landmark panorama around the nest.

Vegetation reduces the foraging efficiency of desert ants Cataglyphis urens, and they prefer unvegetated microhabitats

Abstract Social animals, and ants, in particular, exhibit a range of cooperative behaviors. One such behavior is the rescue of group members, which cannot return to the nest by themselves. However, if several group members need to be rescued, how do ants prioritize whom to save first? Furthermore, when food is offered in parallel, do ants prioritize feeding over rescuing? We studied the rescue behavior of the desert ant Cataglyphis niger. Workers invest more time in rescuing pupae than adult workers, perhaps because the value of brood is higher than that of older workers serving as foragers. Specific rescue behaviors, pulling the trapped individual or digging around it, differed when directed toward adults or pupae: rescuing workers more often pulled pupae whereas they dug more around trapped adults. Rescuing workers did not prioritize living individuals over dead ones or intact workers over injured ones indicating that trapped individuals were recognized chemically rather than by their morphology or behavior. Finally, workers prioritized foraging over rescuing, perhaps because fewer workers specialize in rescue behavior than in foraging. Our analysis indeed revealed that fewer workers both foraged and rescued trapped workers than expected by chance. In conclusion, ants that rescue others exhibit a complex set of behaviors, with varying attention and specific behaviors targeted at different individuals, perhaps according to the colony’s needs. Our study is important for emphasizing a relatively neglected aspect of sociality (rescue of group members) and demonstrates that the attentions of rescues differ based on the trapped nestmate’s life stage.

Abstract Land‐use change from solar energy development may affect desert ecosystems and the soils, plants, and animals therein, yet our understanding of these interactions is nascent. With their ubiquity, criticality as ecosystem constituents, and sensitivity to environmental variation, ants may be useful study organisms for elucidating ecological effects of solar energy development in deserts. Our objectives were to disentangle the response of a desert ant community to solar energy development decisions and test the efficacy of ants as bioindicators at a solar power facility (392 MW) in the Mojave Desert, USA. We used pitfall traps to collect ants in treatments representing different solar energy development decisions, including variably intense site preparation practices: blading (i.e., bulldozing) and mowing, and establishment of undeveloped patches in solar fields, replicated across three power blocks comprising the facility and in undeveloped control sites surrounding the facility. We determined that ant abundance, species richness, Shannon Diversity Index, and functional richness were lower in bladed treatments than in all other treatments and controls. For most taxonomic and functional ant responses, we detected no difference between nonbladed treatments and controls; these results suggest that less intensive site preparation and increased spatial heterogeneity (i.e., undeveloped patches in solar fields) can reduce the negative effects of solar energy development on desert ants. However, our results indicate that ants may serve as useful bioindicators of the severity of anthropogenic disturbance from solar energy development in deserts, and indicator analysis signifies that solar energy infrastructure may negatively affect some species with high ecological value (e.g., harvester ants). Negative effects of solar energy development on ants can have significant implications for desert ecosystem function and integrity, but conservation‐minded solar facility design and construction may lead to avoidance of “bottom‐up” ecological ramifications of increased solar production during the renewable energy transition.